The present invention relates to a method of preparing magnesium alkylphenates, the products obtained by said method, and to their use as detergent-dispersant additives for lubricating oils.
U.S. Pat. Nos. 3,718,589 and 3,932,289 disclose that magnesium alkylphenates can be prepared from alkylphenols by using carbonated magnesium alcoholates as neutralizing or super-alkalinizing agents. Such methods are costly and difficult since the carbonated magnesium alcoholates require preparation from metallic magnesium.
French Pat. No. 2,277,145 (U.S. counterpart, Pat. No. 4,049,560) discloses that magnesium alkylphenates can be prepared by carbonating a mixture containing an alkylphenol, possibly a sulfurized alkylphenol, a sulfonic acid, an alcohol, magnesium hydroxide or active magnesia, as well as a promoter of the ammonium carboxylate type. Such a method does not employ an alkylphenol by itself, but a mixture of alkylphenol and sulfonic acid, which is easier to neutralize, and it requires the presence of a promoter.
Applicant has discovered a method which makes it possible to prepare magnesium alkylphenates by employing an alkylphenol alone (that is to say, not mixed with a sulfonic acid) and active magnesia, and not requiring the use of a promoter.
It is, accordingly, an object of the present invention to provide a process which avoids the disadvantages of the prior art processes.
It is also an object of the present invention to provide a process for the preparation of magnesium alkylphenates which avoids the use of a sulfonic acid and a promoter.
It is a further object of the present invention to provide a process for the preparation of magnesium alkylphenates by employing an alkylphenol alone with active magnesia.
Other objects will be apparent to those skilled in the art from the present description.